Structure of Atom — Chemistry STD 11 Science — Question
Gujarat BoardEnglish MediumSTD 11 ScienceChemistryStructure of Atom1 Mark
MCQ
$f$ Aufbau rule is violated, then $\ce{Ca}^{20}$ will be in :
A
$S-$ block
B
$P-$ block
✓
$D-$ block
D
$F-$ block
✓
Answer
Correct option: C.
$D-$ block
According to the Aufbau principle, electron enters into the lowest energy level $($orbital$),$ before entering into a higher energy level. Hence, according to this principle, the electronic configuration of $\ce{Ca}^{20}$ is $\ce{1 s^2 2 s^2 2 p^6 3 s^2 3 p^6 4 s^2}$, as differentiating electron enters into the $s-$orbital, $\ce{Ca}$ belongs to $s-$ block.
If we don't follow the Aufbau rule, the electronic configuration of $\ce{Ca}^{20}$ would be $\ce{1 s^2 2 s^2 2 p^6 3 s^2 3 p^6 3 d^2}$.
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